This invention relates to air handling systems for use in a building in order to supply air to the interior of a building and, in particular, to such a system employing an axial fan unit.
A number of different air handling systems are known for providing conditioned air to a building's interior. These systems can vary depending upon the size of and requirements of the building. They also differ on the basis of the perceived requirements for heating and cooling in the building. Particularly in systems designed for larger buildings, a concern of the building owner and of the users of the building is that the air handling system be not only efficient for the delivery of conditioned air to each floor of the building but also relatively quiet in its operation.
Relatively sophisticated air handling systems for multi-storey buildings are already known in the heating and air conditioning industry. For example, it is already known to provide a relatively large axial fan on a lower floor of a multi-storey building in order to deliver the required conditioned air through a system of air ducts to the various floors of the building. In order to reduce the sound levels that are produced by the operation of the fan, the fan inlet can be mounted adjacent an inlet attenuator which directs incoming air into the inlet side of the fan. There can also be an outlet attenuator mounted adjacent the outlet side of the fan and connected to one or more air delivery ducts. Both of these attenuators can have exterior walls and specially designed interior walls with sound attenuating material arranged between the interior and exterior walls. One perceived difficulty with these known system is that they generally require a reasonably large room set aside on the lower floor for the air handling system, including the attenuators and, with such systems, difficulties can be encountered in controlling the conditioned air delivered to each floor of the multi-storey building and in modifying the air delivery system when changes are made to the layout of one or more of the floors of the building.
In U.S. Pat. No. 4,418,788 issued Dec. 6, 1983 to Mitco Corporation there is disclosed a composite branch take-off and silencer for an air distribution system. This take-off unit includes two series-coupled sections including a static pressure regain section and a channel section adapted for coupling an input duct to an output duct and branch ducts. With this unit, the input section is located adjacent the axial fan which is generally located at the bottom end while the channel section which is coupled to a main duct for the delivery of air is located in the upper half of the unit. Sound absorbing material is used at several locations in the unit to reduce the amount of sound passing through the unit and into the air ducts.
More recent U.S. Pat. No. 4,874,127 issued Oct. 17, 1989 to W. R. Collier describes a multi-level access flooring system with a working area floor and at least one intermediate floor. A horizontal plenum is formed between an intermediate floor and the building floor. An HVAC unit is mounted on an elevated top floor and this unit has an axial fan and an air outlet located at the bottom thereof. Just above the outlet are arranged evaporator coils. Air from the room enters the HVAC unit through a top grill. As there is no provision for reducing the sound levels emanating from the axial fan, it appears that the climate control system described in this patent specification would be relatively noisy. There is also no provision in this system for mixing fresh air with return air before it is passed through the HVAC unit and delivered to the air distribution plenum and the air outlets.
U.S. Pat. No. 4,646,966 issued Mar. 3, 1987 to Argon Corp. teaches a personalized air conditioning system which employs an air plenum formed by an elevated floor of the building. Air rises from the floor space into an air distribution system which includes an upstanding passageway or column that has upright sidewalls. A small fan is mounted in the column as is an air valve which apparently regulates the air passing upwardly in the column. A plurality of air outlets are provided near the top of the column and are adjustable.
It is an object of the present invention to provide an efficient air handling system that can be provided on each floor of a building, particularly a high-rise building, in order to supply air to the interior.
It is a further object of the present invention to provide a novel air handling system for use in a building having an elevated floor assembly mounted on a principal floor of the building, this assembly including a working area floor which lies above the principal floor so as to provide an air plenum.
It is another object of the present invention to provide an air handling system for use in a building, the system including an air outlet section with a lowermost air outlet, an axial fan unit and an air inlet section that is mounted above the axial fan unit and that has an air mixing chamber arranged to receive airflows entering through air inlet openings.